2018 Kia Optima

Engine complaints dominate the 2018 Optima picture by a wide margin. The most common theme across reports is excessive oil consumption, owners describe adding oil frequently between changes, with some reporting consumption as severe as a quart every few hundred miles. No external leaks are typically found, pointing to internal burning. Many of these same owners report accompanying symptoms: engine misfires, rough running, jerking on acceleration, and loss of power. A check engine code related to knock sensor detection comes up in several reports, and a number of owners describe engines that eventually fail or become undrivable at higher mileages. The electrical system draws a smaller but notable share of complaints, with owners describing unexpected shutdowns and stalling that some trace to repeated battery failure. Steering complaints round out the top three at a lower volume, though the engine oil consumption pattern is clearly the defining issue owners report for this model year.